1. Field
The subject technology relates generally to electromechanical switches, and more specifically to system and method of optical telemetry for electromechanical switches.
2. Background
Many telecommunications systems employ electromechanical switches to pass radio frequency (RF) signals. One application for these types of electromechanical switches is in spacecraft communications wherein an uplink RF signal may be transmitted as a downlink RF signal. These types of telecommunications systems frequently make use of a multi-pole electro-mechanical switch (e.g., a rotary switch) in which a signal provided to a motor, positioned within or without the switch, causes the switch to change its position or state.
In many of these RF switch applications, the electromechanical RF switches are remotely located, such as in an isolated telecommunications switching center or in a spacecraft. Because of the remoteness and inaccessibility of the RF switches, it is important to provide a telemetry system to monitor the status or position of each of the RF switches. In some cases, a sensor portion of the telemetry system is integrated in the same package as the RF switch being monitored to form an integrated electromechanical switch.
In conventional electromechanical switches, the sensor portion includes a number of electromechanical sensor switches where one of the sensor switches is actuated at a given position of the multi-pole electromechanical switch. For example, the sensor portion can include a combination of a magnet and magnetically actuated reed switches (the number of reed switches being equal to the number of poles of the electromechanical switch) in which as the position of the electromechanical switch is changed from a first position to a second position, the magnet moves from a first location above a first reed switch associated with the first position to a second location above a second reed switch associated with the second position. The movement of the magnet causes release (e.g., opening) of the first reed switch and actuation (e.g., closing) of the second reed switch. By monitoring the states of all the reed switches and determining which one of the switches is actuated (e.g., by monitoring their outputs), the telemetry system can determine or verify the position of the multi-pole electromechanical switch.
However, such electromechanical switch telemetry based on electromechanical sensor switches such as reed switches can fail to provide accurate indication of the RF switch position due to a failure of one of the sensor switches. The failure of the sensor switch is often attributable to electromechanical nature of the switch including foreign object debris in the plating of the contact surfaces of the switch.